Sept. 15, 2008 -- Migraine sufferers appear to be at increased risk for stroke, and now a new study may help explain why.
One theory has been that people with migraines develop hardened plaque within the arteries -- known as atherosclerosis -- earlier than people without migraines. Atherosclerosis is a major risk factor for stroke.
But this was not seen in the study, which was the first to use high-resolution ultrasound to examine the hypothesis.
The imaging did not show more plaque buildup in the arteries of the people with migraines. But a review of medical records did reveal an increase in vein-related blood clots (such as deep vein thrombosis, DVT, and pulmonary embolism) in these people, compared to people without migraines.
The findings must be confirmed, says study researcher Stefan Kiechl, MD. But they could help explain the link between migraine and stroke.
"This is very strong evidence that atherosclerosis is not driving this link," he tells WebMD. "And the association between migraine and blood clots is a new and exciting finding."
Migraines and Stroke
The study included 574 Italians age 55 and older, including 111 people with a history of migraines followed for five years.
Researchers reviewed the medical records of all the participants and used ultrasound to determine the extent of plaque buildup within their arteries.
More than twice as many people with migraines -- 19% vs. 8% -- also had a history of venous thrombosis.
But migraine sufferers were no more likely to have atherosclerosis than study participants without migraines.
Venous thrombosis has been linked to an increased risk for stroke in several large and well-respected studies, Kiechl notes.
His study appears in the Sept. 16 issue of the journal Neurology.
Mutation May Explain Link
More than 23 million Americans suffer from migraines, and three out of four are women.
Over the last decade, an increasing number of studies have shown an increased risk for stroke among women and men with migraines, especially those with a migraine subtype known as migraine with aura.
Migraine with aura has also been linked to an increased risk for a genetic disorder associated with blood clots, known as the factor V Leiden mutation.
This mutation might explain the migraine-stroke link, or the link may be due to a stress reaction that promotes blood clotting, Kiechl says.
Neurologist Stephen Silberstein, MD, tells WebMD that the observations in the study by Kiechl and colleagues should change the thinking about migraines and stroke.
"The venous thrombosis link was a surprise and it is very interesting," the Jefferson Medical College professor of neurology tells WebMD. "We don't know if this is because of this genetic mutation or if something else is going on. But it is a very important observation."